Neratinib is an investigational, orally administered, irreversible inhibitor of the ErbB1 (EGFR), ErbB2 (HER2) and ErbB4 (HER4) kinases. Neratinib permanently inactivates the ErbB kinases. Inhibited HER2 activities include downstream signal transduction events and cell cycle regulatory pathways, such as the cell division cycle, ultimately resulting in decreased cell proliferation.
ErbB2 belongs to the ErbB family of receptor tyrosine kinases, which has been implicated in a variety of human cancers
, including cancers of the breast. HER2 positive breast cancer is identified by the overexpression of human epidermal growth factor receptor-2 (HER2) protein in tumor tissue and results in an increased rate of cell proliferation.